ORM for C++: Comparison and Usage Examples

ORM for C++: Comparison and Examples

In the world of C++, working with databases has historically been more low-level than in languages like Python or Java. However, modern projects require convenience and productivity, so developers are increasingly turning to ORM (Object-Relational Mapping). ORM for C++ allows you to work with tables as regular C++ objects, automatically generate SQL queries, and manage schema migrations. In this article, we will look at five popular libraries: ODB, SQLiteCpp, SOCI, cppdb, and sqlpp11, compare their features, and provide practical examples.

1. ODB — The Corporate Standard

ODB is a powerful ORM framework for C++ that supports many DBMS: MySQL, PostgreSQL, SQLite, Oracle, SQL Server. The main feature is code generation: you describe the model in a header file with annotations, and the ODB compiler (odb) creates the code for working with the database.

// person.hxx#pragma once#include <string>#include <odb/core.hxx>

#pragma db objectclass Person {public:    Person() {}    Person(const std::string& name, int age)        : name_(name), age_(age) {}

    const std::string& getName() const { return name_; }    int getAge() const { return age_; }

private:    friend class odb::access;    #pragma db id auto    unsigned long id_;    std::string name_;    int age_;};

After running odb -d mysql person.hxx, files with the implementation are generated. Then we use the standard pattern:

#include <odb/database.hxx>#include <odb/mysql/database.hxx>#include "person-odb.hxx"

int main() {    auto db = std::make_shared<odb::mysql::database>("user", "pass", "mydb");    Person p("Alice", 30);    db->persist(p);    // Loading    auto loaded = db->load<Person>(1);    return 0;}

Pros: full ORM, migration support, lazy loading, transaction handling. Cons: complex setup, need for code generation, heavyweight for small projects.

2. SQLiteCpp — Lightweight and Simple

SQLiteCpp is a C++ RAII-style wrapper over SQLite3. It is not a full-fledged ORM, but it provides a convenient interface for working with queries.

#include <SQLiteCpp/Database.h>#include <SQLiteCpp/Statement.h>

int main() {    SQLite::Database db("test.db", SQLite::OPEN_READWRITE | SQLite::OPEN_CREATE);    db.exec("CREATE TABLE IF NOT EXISTS person (id INTEGER PRIMARY KEY, name TEXT, age INT)");        SQLite::Statement insert(db, "INSERT INTO person (name, age) VALUES (?, ?)");    insert.bind(1, "Bob");    insert.bind(2, 25);    insert.exec();        // Reading    SQLite::Statement query(db, "SELECT * FROM person WHERE age > ?");    query.bind(1, 20);    while (query.executeStep()) {        std::cout << query.getColumn(1) << " " << query.getColumn(2) << "";    }    return 0;}

Pros: minimalistic, no code generation required, works only with SQLite. Cons: no object mapping, manual SQL writing.

3. SOCI — Universal Abstraction Layer

SOCI (The C++ Database Access Library) is not an ORM in the pure sense, but an abstraction over different DBMS (SQLite, PostgreSQL, MySQL, Oracle). It provides a convenient syntax for executing queries and binding results to C++ structures.

#include <soci/soci.h>#include <soci/sqlite3.h>

struct Person {    int id;    std::string name;    int age;};

int main() {    soci::session sql(soci::sqlite3, "test.db");    sql << "CREATE TABLE person (id INTEGER PRIMARY KEY, name TEXT, age INT)";        Person p{1, "Charlie", 35};    sql << "INSERT INTO person (id, name, age) VALUES (:id, :name
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